Well, I think comfortably_numb is probably right about what Smart HDR is. I had to read between the lines on AVSForum, but it definitely seems like it is interpolated HDR. HDR standards like HDR10 and DV will show up as such, while Smart HDR is a picture setting that makes SDR look more HDR-like. An example post where it is being discussed:I'm gonna need more than a Reddit post. Looking at TCL's website, but it is useless so far.

TCL 2023 QM8 Mini LED Google TV - Owners Thread
The 2023 TCL QM8 is available now from Best Buy and Amazon with delivery as soon as this weekend! There's too many threads about the new 2023 TCL TVs, so I thought an owners thread for their flagship QM8 model would be helpful. V295 firmware: https://www.avsforum.com/posts/63258559/ V291...
The TCL manual, such as it is, just says "Smart HDR- Powerful and vivid picture."